Zero-Shot Ranking via MLM (ZS-MLM). Masked Language Modeling (MLM) is used extensively for pretraining LLMs [1]}, [2]}, which involves predicting a masked word (i.e. [mask]) given the surrounding context words. This objective can be extended for zero-shot ranking using various contextual prompts. For ORR, we use the prompt in <room>, usually you put <object> <spatial-preposition> [mask] to rank receptacles given an object, a room, and a spatial preposition (e.g. in or on). For OR, we use the prompt in a household, it is likely that you can find <object> in the room called [mask].
